Light emitting device and electronic equipment

ABSTRACT

A highly reliable light-emitting device is provided in which an organic light-emitting device is not degraded by oxygen, moisture, and the like. The organic light-emitting device is press-fit in vacuum using a wrapping film ( 105 ) that is covered with a DLC film (or a silicon nitride film, an AlN film, a film of a compound expressed as AlN X O Y ) ( 106 ) containing Ar. The organic light-emitting device thus can be completely shut off from the outside, and moisture, oxygen, or other external substances that accelerate degradation of an organic light emitting layer can be prevented from entering the organic light-emitting device.

This application is a continuation of U.S. application Ser. No.10/896,436 filed on Jul. 22, 2004 now U.S. Pat. No. 6,956,325 which is acontinuation of U.S. application Ser. No. 10/077,370 filed on Feb. 15,2002 now U.S. Pat. No. 6,822,391.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an OLED (organic light-emitting device)panel obtained by forming an OLED on a substrate and sealing the OLEDbetween the substrate and a cover member. The invention also relates toan OLED module in which an IC including a controller, or the like, ismounted to the OLED panel. In this specification, ‘light-emittingdevice’ is the generic term for the OLED panel and for the OLED module.Electronic equipment using the light-emitting device is also included inthe present invention.

2. Description of the Related Art

Being self-luminous, OLEDs eliminate the need for a backlight that isnecessary in liquid crystal display devices (LCDs) and thus make it easyto manufacture thinner devices. Also, the self-luminous OLEDs are highin visibility and have no limit in terms of viewing angle. These are thereasons for attention that light-emitting devices using the OLEDs arereceiving in recent years as display devices to replace CRTs and LCDs.

An OLED has a layer containing an organic compound (organiclight-emitting material) that provides luminescence(electroluminescence) when an electric field is applied (the layer ishereinafter referred to as organic light-emitting layer), in addition toan anode layer and a cathode layer. Luminescence obtained from organiccompounds is classified into light emission upon return to the basestate from singlet excitation (fluorescence) and light emission uponreturn to the base state from triplet excitation (phosphorescence). Alight-emitting device according to the present invention can use one orboth types of the light emission.

In this specification, all the layers that are provided between an anodeand a cathode together make an organic light emitting layer.Specifically, the organic light emitting layer includes a light emittinglayer, a hole injection layer, an electron injection layer, a holetransporting layer, an electron transporting layer, etc. A basicstructure of an OLED is a laminate of an anode, a light emitting layer,and a cathode layered in this order. The basic structure can be modifiedinto a laminate of an anode, a hole injection layer, a light emittinglayer, and a cathode layered in this order, or a laminate of an anode, ahole injection layer, a light emitting layer, an electron transportinglayer, and a cathode layered in this order.

The problem in putting a light-emitting device using the OLED intopractice is degradation of the device by heat, light, moisture, oxygen,and other causes.

When manufacturing a light-emitting device with OLED, in general, theOLED is formed after a wiring line and a semiconductor element areformed in a pixel portion. Once the OLED is formed, a first substrate onwhich the OLED is placed is bonded to a second substrate (made of metalor glass) for sealing (packaging) the OLED so that the OLED is notexposed to the outside air. A resin or the like is used to bond thesubstrates and nitrogen or inert gas fills the space between thesubstrates. However, oxygen easily reaches the OLED sealed as above bythe substrates and a resin through the slightest crack in the package.Furthermore, moisture finds no difficulty in seeping into the OLEDthrough the resin used in bonding and sealing. This causes non-lightemission portions called dark spots, which grow larger with time andemit no light, which becomes a problem.

SUMMARY OF THE INVENTION

The present invention has been made to solve the above problem and anobject of the present invention is therefore to provide a light-emittingdevice using a highly reliable OLED. Another object of the presentinvention is to provide electronic equipment with a highly reliabledisplay unit by employing such light-emitting device with the OLED forits display unit.

The present invention relates to a technique for sealing an OLED that isplaced on a substrate having an insulating surface. To seal the OLED,the present invention employs vacuum sealing using a film that isprovided, on one side (inside) at least, with a thin film low in gastransmissivity (typically, a thin film mainly containing carbon, asilicon oxynitride film, a silicon nitride film, a film of a compoundexpressed as AlN_(X)O_(Y), a AlN film, or a laminate of these films).

In the present invention, a film low in gas transmissivity is used toprovide a film while adding a rare gas element to reaction gas in orderto give the film flexibility. The present invention is characterized inthat a thin film low in gas transmissivity (typically, a thin filmmainly containing carbon, a silicon oxynitride film, a silicon nitridefilm, a film of a compound expressed as AlN_(X)O_(Y), a AlN film, or alaminate of these films) contains a rare gas element to ease theinternal stress in the film and to make the film flexible, and that afilm provided, at least on one side (inside), with the thin film is usedto vacuum-seal a light-emitting device having an OLED.

A film obtains flexibility by containing rare gas. Therefore, the thinfilm used to provide the wrapping film is prevented from developing acrack or peeling off when thermally press-fit in vacuum. Moreover, thefilm used as a lining can improve the heat resistance and mechanicalstrength of the wrapping film.

A structure of the present invention disclosed in this specification isa light-emitting device characterized in that:

the device includes a TFT, an active matrix substrate on which a lightemitting element having the TFT is formed, a desiccant, and a protectiveunit wrapping the active matrix substrate; and

the protective unit is a film at least partially provided with a thinfilm that contains a rare gas element and mainly contains carbon. Inthis specification, a substrate on which an OLED is formed is called anactive matrix substrate.

In the above structure, the light emitting element has an anode, acathode, and an EL material sandwiched between the anode and thecathode.

In the above structure, the protective unit is brought into contact withthe active matrix substrate by vacuum press-fitting. Accordingly, theprotective unit has flexibility to a certain degree. Any film can beused for this protective unit as long as it is an excellent gas barrierand is transparent or translucent with respect to visible light. Forexample, the protective unit may be a film entirely covered with a thinfilm that contains carbon as its main component, or a film provided witha thin film that contains carbon as its main component on one side(inside or outside).

The present invention is characterized in that the thin film thatcontains carbon as its main component is a DLC (diamond like carbon)film with a thickness of 3 to 50 nm. A DLC film has a SP³ bond as thebond between carbon atoms in terms of short range order.Macroscopically, a DLC film has an amorphous structure. A DLC film iscomposed of 70 to 95 atomic % of carbon and 5 to 30 atomic % ofhydrogen, which makes the DLC film very hard and excellent ininsulating. A DLC film as such is also characterized by having a lowtransmissivity for steam, oxygen, and other gas. A DLC film is known tohave a hardness of 15 to 25 GPa when measured by a microhardness tester.

A DLC film is formed by plasma CVD, microwave CVD, electron cyclotronresonance (ECR) CVD, sputtering, etc. Any of these methods can provide aDLC film having an appropriate adhesion. A DLC film is formed by settinga substrate as the cathode. When a negative bias is applied and some ofion impact is utilized, a dense and hard DLC film can be obtained.

Reaction gas used in forming a DLC film by plasma CVD ishydrocarbon-based gas, for example, CH₄, C₂H₂, or C₆H₆. The reaction gasis ionized by glow discharge and the ions are accelerated to impactagainst a cathode to which a negative self-bias is applied. As a result,a dense and flat DLC film can be obtained.

This DLC film is characterized by being an insulating film which istransparent or translucent to visible light.

In this specification, being transparent to visible light means to havea transmissivity of 80 to 100% for visible light whereas beingtranslucent to visible light means to have a transmissivity of 50 to 80%for visible light.

A silicon oxynitride film may be used instead of the above DLC film. Inthis case, the protective unit is a film at least partially providedwith a silicon oxynitride film.

A silicon nitride film may be used instead of the above DLC film. Inthis case, the protective unit is a film at least partially providedwith a silicon nitride film.

An AlN film may be used instead of the above DLC film. In this case, theprotective unit is a film at least partially provided with an AlN film.

An AlN_(X)O_(Y) film may be used instead of the above DLC film. In thiscase, the protective unit is a film at least partially provided with anAlN_(X)O_(Y) film.

A laminate having in combination a DLC film, a silicon oxynitride film,a silicon nitride film, an AlN film, and a film of an AlN_(X)O_(Y) filmmay also be used. In this case, the protective unit is a film at leastpartially provided with the laminate.

Preferably, the silicon nitride film, the AlN film, or the AlN_(X)O_(Y)film is formed by sputtering and rare gas is introduced to the chamberso that the formed film contains a rare gas element (typically Ar) in aconcentration of 0.1 atomic % or higher, more desirably, 1 to 30 atomic% or higher.

In the above structure, a desiccant is preferably placed between theactive matrix substrate and the protective unit sealed in vacuum inorder to prevent degradation of the light emitting element. A suitabledesiccant is barium oxide, a calcium oxide, silica gel, or the like. Thedesiccant is placed before or after a flexible printed substrate isbonded. Alternatively, the desiccant may be set in a flexible film ofthe flexible printed substrate and then the flexible printed substrateis bonded. Preferably, the desiccant is placed near the location wherethe protective unit is press-fit in vacuum.

A structure of the present invention for obtaining the above structureis a method of manufacturing a light-emitting device, characterized bycomprising the steps of:

forming a light emitting element on a substrate that has an insulatingsurface;

bonding a flexible printed substrate to the edge of the substrate; and

sealing in vacuum the light emitting element and a part of the flexibleprinted substrate using a film that is covered with a thin film mainlycontaining carbon.

In the above structure, the step of forming the light emitting elementmay be followed by a step of thinning the thickness of the substrate. Ifthe substrate is thinned, the thinning step is preferably followed bythe step of bonding the flexible printed substrate to the edge of theformer substrate.

In the above structures, the method is characterized by comprising astep of placing a desiccant that is in contact with the flexible printedsubstrate before the vacuum sealing step. The vacuum sealing stepemploys thermal press-fitting.

In the above structures, the thin film mainly containing carbon is a DLCfilm containing a rare gas element in a concentration of 0.1 atomic % orhigher, preferably 1 to 30 atomic %.

In the above structures, the rare gas element is one or more kinds ofelements selected from the group consisting of He, Ne, Ar, Kr, and Xe.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A to 1C are diagrams showing a process of manufacturing alight-emitting device;

FIG. 2 is a diagram showing a process of manufacturing a light-emittingdevice;

FIG. 3 is a diagram showing an apparatus for forming a DLC film (plasmaCVD apparatus);

FIGS. 4A and 4B are a top view and a sectional view of an OLED module,respectively;

FIGS. 5A to 5D are diagrams showing a process of manufacturing an activematrix substrate;

FIGS. 6A to 6C are diagrams showing a process of manufacturing an activematrix substrate;

FIGS. 7A and 7B are diagrams showing a process of manufacturing anactive matrix substrate;

FIGS. 8A to 8H are diagrams showing examples of electronic equipment;

FIG. 9 is a diagram showing a film forming apparatus that usessputtering;

FIG. 10 is a graph showing the transmissivity of an AlN_(X)O_(Y) (X<Y)film;

FIG. 11 is a graph showing the transmissivity of an AlN film; and

FIG. 12 is a graph showing the moisture permeability of various kinds offilms.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiment Modes 1 and 2 will be described below with reference to FIGS.1A to 3.

Embodiment Mode 1

First, a substrate having an insulating surface is prepared. On thesubstrate, a light emitting element, here, OLED, and a lead-outelectrode 102 are provided. The lead-out electrode 102 connects the OLEDto an external power supply. If light from the light emitting element istransmitted through the substrate, used as the substrate having aninsulating surface is a light transmissive substrate such as a glasssubstrate, a crystallized glass substrate, or a plastic substrate. Iflight from the light emitting element does not travel through thesubstrate, a ceramic substrate, a semiconductor substrate, a metalsubstrate, and the like may be used.

In order to reduce the weight of the device, etch off treatment isperformed on the substrate and the substrate is thinned. A substrate 101having the OLED formed thereon is thus obtained. The etch off treatmentmay not always be necessary. Next, a flexible printed substrate (FPC)103 is bonded to the substrate 101 to be electrically connected to thelead-out electrode 102. (FIG. 1A)

A desiccant 104 is placed on the substrate 101 having the OLED formedthereon in order to prevent degradation of the OLED due to oxygen,moisture, and the like. The desiccant 104 is a hygroscopic substance(preferably calcium oxide or barium oxide), or a substance capable ofadsorbing oxygen. Here, the desiccant 104 is placed so as to come intocontact with the FPC 103 and an end face of the substrate 101. Thisprevents a protective unit from being locally stretched and damaged in alater step of vacuum press-fitting.

The protective unit that can serve as a gas barrier is thermallypress-fit in vacuum to seal the OLED and further prevent degradation ofthe OLED due to oxygen, moisture, and the like. The protective unit canbe any film which is transparent or translucent to visible light andwhich can be press-fit in vacuum. FIG. 1B shows the protective unitbefore vacuum press-fitting.

The protective unit used here is a wrapping film 105 that is coveredwith a DLC film 106 containing rare gas (Ar). The wrapping film 105 thatis covered with a DLC film 106 containing Ar wraps the substrate 101with the OLED formed thereon, the desiccant 104, and a part of theflexible printed substrate 103 for vacuum packing. Shown here is anexample of a wrapping film covered with a DLC film except the portionfor press-fitting. However, the wrapping film may be merely providedwith a DLC film on one side (inside or outside). The film used toprovide or cover the wrapping film is not limited to a single-layer filmbut may be a multi-layered film.

The DLC film 106 containing rare gas (Ar) is formed in a film formingapparatus that uses plasma CVD and is shown in FIG. 3. A chamber 301 isexhausted to reach vacuum and a mixture of CH₄ gas and Ar gas, or amixture of C₂H₆ gas and Ar gas, is introduced as raw material gas intothe chamber. Then a DLC film (containing Ar) 306 is formed on thesurface of a wrapping film 305. The wrapping film is fixed by a holder307 between an electrode 302 that is connected to an RF power supply 304and an electrode 303. Note that the DLC film 306 is not formed onportions of the wrapping film 305 that are in contact with the holder307. The present invention uses these portions where the DLC film is notformed for thermal press-fitting. FIG. 1C shows the protective unitafter vacuum press-fitting. The wrapping film used here is like a sackor an empty box. Alternatively, the wrapping film may be composed of twosheets laid on top of each other and the four sides thereof are allpress-fit. A preferable material of the wrapping film is one that can bebonded also to a flexible tape in thermal press-fitting. The materialusable as the wrapping film is a resin material (polyethyleneterephthalate (PET), polyether sulfon (PES), polyethylene naphthalate(PEN), polycarbonate (PC), nylon, polyether ether ketone (PEEK),polysulfon (PSF), polyether imide (PEI), polyarylate (PAR),polybuthylene terephthalate (PBT), etc.). Typically, thermoplastic, aPVF (polyvinyl fluoride) film, a Mylar film, or an acrylic resin film isused. After thermal press-fitting, the press-fit portions may be furthersealed using an adhesive, and the FPC may be bonded to the protectiveunit with an adhesive.

Once the OLED is formed on the substrate, the above steps are conducteddesirably avoiding exposure of the OLED to the outside air as much aspossible.

In this way, the present invention can provide a light-emitting deviceusing an OLED whose reliability is increased by controlling degradationdue to moisture, oxygen, and the like.

Embodiment Mode 2

A description given here with reference to FIG. 2 is about an example ofa light-emitting device in which an OLED is sealed using a sealingsubstrate 200 and then further sealed by a protective unit.

In FIG. 2, 200 denotes a sealing substrate, 201, a substrate having anOLED formed thereon, 202, a lead-out electrode, 203, an FPC, 204, adesiccant, 205, a wrapping film, and 206, a DLC film containing Ar.Although the film 206 here is a DLC film containing Ar, the DLC film maybe replaced by a silicon oxynitride film containing Ar, a siliconnitride film containing Ar, a Ar-containing film of a compound expressedas AlN_(X)O_(Y), or a AlN film containing Ar.

By containing Ar, the film can be flexible and therefore can beprevented from developing a crack or peeling off when used to providethe wrapping film and thermally press-fit in vacuum.

Though not shown in the drawing, the sealing substrate 200 is bonded tothe substrate 201 with an adhesive. The space between the sealingsubstrate 200 and the substrate 201 is filled with a resin, nitrogen, orinert gas. If light from the light emitting element is transmittedthrough the sealing substrate 200, used as the sealing substrate is alight transmissive substrate such as a glass substrate, a crystallizedglass substrate, or a plastic substrate. If light from the lightemitting element does not travel through the sealing substrate 200, aceramic substrate, a semiconductor substrate, a metal substrate, and thelike may be used. The sealing substrate 200 may not always take theshape of a plate but may resemble a lid.

The desiccant 204 here is placed on the substrate 201 between the FPC203 and the sealing substrate 201, so that the protective unit isprevented from being locally stretched and damaged in a later step ofvacuum press-fitting.

The present invention structured as above will be further detailedthrough the following Embodiments.

Embodiment 1

FIG. 4A is a top view of an OLED module manufactured. FIG. 4B is asectional view schematically showing one pixel of the module of FIG. 4A.

A pixel portion 404 is arranged on a substrate 401 such that a sourceline driving circuit 402 and a gate line driving circuit 403respectively run parallel to two sides of the pixel portion. The pixelportion 404, the source line driving circuit 402, and the gate linedriving circuit 403 each have a plurality of TFTs. FIG. 4B shows, asrepresentatives of those TFTs, a driving circuit TFT (composed of ann-channel TFT and a p-channel TFT in FIG. 4B) 411 included in the sourceline driving circuit 402 and a driving TFT (a TFT for controlling acurrent flowing into the OLED) 412 included in the pixel portion 404.The TFTs 411 and 412 are formed on a base film 410.

In this embodiment, the n-channel TFT and the p-channel TFT thatconstitute the driving circuit TFT 411 are manufactured by a knownmethod, and a p-channel TFT manufactured by a known method is used forthe driving TFT 412. The pixel portion 404 is provided with a capacitorstorage (not shown) connected to a gate electrode of the driving TFT412.

Formed on the driving circuit TFT 411 and the driving TFT 412 is aninterlayer insulating film (planarization film) 421, on which a pixelelectrode (anode) 413 is formed to be electrically connected to a drainof the driving TFT 412. The pixel electrode 413 is formed of atransparent conductive film having a large work function. Examples ofthe usable transparent conductive film material include a compound ofindium oxide and tin oxide, a compound of indium oxide and zinc oxide,zinc oxide alone, tin oxide alone, and indium oxide alone. A transparentconductive film formed of one of these materials and doped with galliummay also be used for the pixel electrode.

An insulating film 422 is formed on the pixel electrode 413. An openingis formed in the insulating film 422 above the pixel electrode 413. Atthe opening above the pixel electrode 413, an organic light emittinglayer 414 is formed. The organic light emitting layer 414 is formed of aknown organic light emitting material or inorganic light emittingmaterial. Either low molecular weight (monomer) organic light emittingmaterials or high molecular weight (polymer) organic light emittingmaterials can be used for the organic light emitting layer.

The organic light emitting layer 414 is formed by a known evaporationtechnique or application technique. The organic light emitting layer mayconsist solely of a light emitting layer. Alternatively, the organiclight emitting layer may be a laminate having, in addition to a lightemitting layer, a hole injection layer, a hole transporting layer, anelectron transporting layer, and an electron injection layer in anycombination.

A cathode 415 is formed on the organic light emitting layer 414 from alight-shielding conductive film (typically, a conductive film mainlycontaining aluminum, copper, or silver, or a laminate consisting of theabove conductive film and other conductive films). Desirably, moistureand oxygen are removed as much as possible from the interface betweenthe cathode 415 and the organic light emitting layer 414. Somecontrivance is therefore needed for the removal. For example, theorganic light emitting layer 414 is formed in a nitrogen or rare gasatmosphere and then the cathode 415 is successively formed withoutkeeping the substrate from moisture and oxygen. This embodiment uses amulti-chamber system (cluster tool system) film forming apparatus toachieve the film formation described above. The cathode 415 receives agiven voltage.

An OLED 423 composed of the pixel electrode (anode) 413, the organiclight emitting layer 414, and the cathode 415 is thus formed. Aprotective film 424 is formed on the insulating film 422 so as to coverthe OLED 423. The protective film 424 is effective in preventing oxygenand moisture from entering the OLED 423.

Denoted by reference numeral 409 is a lead-out wiring line connected toa power supply line, and is electrically connected to a source region ofthe driving TFT 412. The lead-out wiring line 409 is electricallyconnected to an FPC wiring line of an FPC 405 through an anisotropicconductive film. The anisotropic conductive film has a conductivefiller. At the same time the pixel electrode 413 is formed, a conductivefilm is formed so as to come into contact with the top face of thelead-out wiring line. The conductive filler electrically connects theconductive film on the substrate 401 to the FPC wiring line on the FPC405 upon thermal press-fitting of the substrate 401 and the FPC 405.

Denoted by reference numeral 406 is a wrapping film for wrapping thesubstrate on which the OLED is formed. The wrapping film 406 is, byvacuum press-fitting, brought into contact with the substrate 401 andthe OLED 423 formed on the substrate so as to prevent moisture, oxygen,and the like from entering the OLED 423. The wrapping film 406 iscovered with a DLC film 400 containing Ar.

By containing rare gas, a film can be flexible and therefore the DLCfilm 400 can be prevented from developing a crack or peeling off whenused to provide the wrapping film 406 and thermally press-fit in vacuum.

Denoted by reference numeral 407 is a desiccant, which is a hygroscopicsubstance (preferably calcium oxide or barium oxide), or a substancecapable of adsorbing oxygen. Here, the desiccant 407 is placed so as tocome into contact with the FPC 405 and an end face of the substrate 401.This prevents a protective unit from being locally stretched and damagedin the vacuum press-fitting step.

The thus manufactured OLED module that is an organic light emittingdisplay device can be used as a display unit in various electronicequipment.

Embodiment 2

Next, described with reference to FIGS. 5 to 7 is an example of a methodof manufacturing a substrate (active matrix substrate) using thelight-emitting device of the present invention. Here, the method ofsimultaneously forming, on the same substrate, the switching TFT and thedriving TFT of the pixel portion, and the TFTs of a driving portionprovided surrounding the pixel portion is described in detail accordingto steps.

This embodiment uses a substrate 500 of a glass such as bariumborosilicate glass or aluminoborosilicate glass as represented by theglass #7059 or the glass #1737 of Corning Co. There is no limitation onthe substrate 500 provided it has a property of transmitting light, andthere may be used a quartz substrate. There may be further used aplastic substrate having heat resistance capable of withstanding thetreatment temperature of this embodiment.

Referring next to FIG. 5A, a base film 501 comprising an insulating filmsuch as silicon oxide film, silicon nitride film or silicon oxynitridefilm is formed on the substrate 500. In this embodiment, the base film501 has a two-layer structure. There, however, may be employed astructure in which a single layer or two or more layers are laminated onthe insulating film. The first layer of the base film 501 is a siliconoxynitride film 501 a formed maintaining a thickness of from 10 to 200nm (preferably, from 50 to 100 nm) relying upon a plasma CVD method byusing SiH₄, NH₃ and N₂O as reaction gases. In this embodiment, thesilicon oxynitride film 501 a (having a composition ratio of Si=32%,O=27%, N=24%, H=17%) is formed maintaining a thickness of 50 nm. Thesecond layer of the base film 501 is a silicon oxynitride film 501 bformed maintaining a thickness of from 50 to 200 nm (preferably, from100 to 150 nm) relying upon the plasma CVD method by using SiH₄ and N₂Oas reaction gases. In this embodiment, the silicon oxynitride film 501 b(having a composition ratio of Si=32%, O=59%, N=7%, H=2%) is formedmaintaining a thickness of 100 nm.

Then, semiconductor layers 502 to 505 are formed on the base film 501.The semiconductor layers 502 to 505 are formed by forming asemiconductor film having an amorphous structure by a known means(sputtering method, LPCVD method or plasma CVD method) followed by aknown crystallization processing (laser crystallization method, heatcrystallization method or heat crystallization method using a catalystsuch as nickel), and patterning the crystalline semiconductor film thusobtained into a desired shape. The semiconductor layers 502 to 505 areformed in a thickness of from 25 to 80 nm (preferably, from 30 to 60nm). Though there is no limitation on the material of the crystallinesemiconductor film, there is preferably used silicon or asilicon-germanium (Si_(X)Ge_(1-x)(X=0.0001 to 0.02)) alloy. In thisembodiment, the amorphous silicon film is formed maintaining a thicknessof 55 nm relying on the plasma CVD method and, then, a solutioncontaining nickel is held on the amorphous silicon film. The amorphoussilicon film is dehydrogenated (500° C., one hour), heat-crystallized(550° C., 4 hours) and is, further, subjected to the laser annealing toimprove the crystallization, thereby to form a crystalline silicon film.The crystalline silicon film is patterned by the photolithographicmethod to form semiconductor layers 502 to 505.

The semiconductor layers 502 to 505 that have been formed may further bedoped with trace amounts of an impurity element (boron or phosphorus) tocontrol the threshold value of the TFT.

In forming the crystalline semiconductor film by the lasercrystallization method, further, there may be employed an excimer laserof the pulse oscillation type or of the continuously light-emittingtype, a YAG laser or a YVO₄ laser. When these lasers are to be used, itis desired that a laser beam emitted from a laser oscillator is focusedinto a line through an optical system so as to fall on the semiconductorfilm.

Then, a gate insulating film 506 is formed to cover the semiconductorlayers 502 to 505. The gate insulating film 506 is formed of aninsulating film containing silicon maintaining a thickness of from 40 to150 nm by the plasma CVD method or the sputtering method. In thisembodiment, the gate insulating film is formed of a silicon oxynitridefilm (composition ratio of Si=32%, O=59%, N=7%, H=2%) maintaining athickness of 110 nm by the plasma CVD method. The gate insulating filmis not limited to the silicon oxynitride film but may have a structureon which is laminated a single layer or plural layers of an insulatingfilm containing silicon.

When the silicon oxide film is to be formed, TEOS (tetraethylorthosilicate) and O₂ are mixed together by the plasma CVD method, andare reacted together under a reaction pressure of 40 Pa, at a substratetemperature of from 300 to 400° C., at a frequency of 13.56 MHz and adischarge electric power density of from 0.5 to 0.8 W/cm². The thusformed silicon oxide film is, then, heat annealed at 400 to 500° C.thereby to obtain the gate insulating film having good properties.

Then, a heat resistant conductive layer 507 is formed on the gateinsulating film 506 maintaining a thickness of from 200 to 400 nm(preferably, from 250 to 350 nm) to form the gate electrode. Theheat-resistant conductive layer 507 may be formed as a single layer ormay, as required, be formed in a structure of laminated layers of plurallayers such as two layers or three layers. The heat resistant conductivelayer contains an element selected from Ta, Ti and W, or contains analloy of the above element, or an alloy of a combination of the aboveelements. The heat-resistant conductive layer is formed by thesputtering method or the CVD method, and should contain impurities at adecreased concentration to decrease the resistance and should,particularly, contain oxygen at a concentration of not higher than 30ppm. In this embodiment, the W film is formed maintaining a thickness of300 nm. The W film may be formed by the sputtering method by using W asa target, or may be formed by the hot CVD method by using tungstenhexafluoride (WF₆).

Next, a mask 508 is formed by a resist relying upon thephotolithographic technology. Then, a first etching is executed. As theetching gas, chlorine type gas such as Cl₂, BCl₃, SiCl₄, and CCl₄ orfluorine gas such as CF₄, SF₆, and NF₃, or O₂ can be appropriately used.This embodiment uses an ICP etching device, uses Cl₂ and CF₄ as etchinggases, and forms a plasma with RF (13.56 MHz) electric power of 3.2W/cm² under a pressure of 1 Pa. The RF (13.56 MHz) electric power of 224mW/cm² is supplied to the side of the substrate (sample stage), too,whereby a substantially negative self bias voltage is applied. Underthis condition, the W film is etched at a rate of about 100 nm/min. Thefirst etching treatment is effected by estimating the time by which theW film is just etched relying upon this etching rate, and is conductedfor a period of time which is 20% longer than the estimated etchingtime.

The conductive layers 509 to 512 having a first tapered shape are formedby the first etching treatment. The conductive layers 509 to 512 aretapered at an angle of from 15 to 30°. To execute the etching withoutleaving residue, over-etching is conducted by increasing the etchingtime by about 10 to 20%. The selection ratio of the silicon oxynitridefilm (gate insulating film 506) to the W film is 2 to 4 (typically, 3).Due to the over etching, therefore, the surface where the siliconoxynitride film is exposed is etched by about 20 to about 50 nm (FIG.5B).

Then, a first doping treatment is effected to add an impurity element ofa first type of electric conduction to the semiconductor layer. Here, astep is conducted to add an impurity element for imparting the n-type. Amask 508 forming the conductive layer of a first shape is left, and animpurity element is added by the ion-doping method to impart the n-typein a self-aligned manner with the conductive layers 509 to 512 having afirst tapered shape as masks. The dosage is set to be from 1×10¹³ to5×10¹⁴ atoms/cm² so that the impurity element for imparting the n-typereaches the underlying semiconductor layer penetrating through thetapered portion and the gate insulating film 506 at the ends of the gateelectrode, and the acceleration voltage is selected to be from 80 to 160keV. As the impurity element for imparting the n-type, there is used anelement belonging to the Group 15 and, typically, phosphorus (P) orarsenic (As). Phosphorus (P) is used, here. Due to the ion-dopingmethod, an impurity element for imparting the n-type is added to thefirst impurity regions 514 to 517 over a concentration range of from1×10²⁰ to 1×10²¹ atoms/cm³ (FIG. 5C).

In this step, the impurities turn down to the lower side of theconductive layers 509 to 512 of the first shape depending upon thedoping conditions, and it often happens that the first impurity regions514 to 517 are overlapped on the conductive layers 509 to 512 of thefirst shape.

Next, the second etching treatment is conducted as shown in FIG. 5D. Theetching treatment, too, is conducted by using the ICP etching device,using a mixed gas of CF₄ and Cl₂ as an etching gas, using an RF electricpower of 3.2 W/cm² (13.56 MHz), a bias power of 45 mW/cm² (13.56 MHz)under a pressure of 1.0 Pa. Under this condition, there are formed theconductive layers 518 to 521 of a second shape. The end portions thereofare tapered, and the thickness gradually increases from the ends towardthe inside. The rate of isotropic etching increases in proportion to adecrease in the bias voltage applied to the side of the substrate ascompared to the first etching treatment, and the angle of the taperedportions becomes 30 to 60°. The mask 508 is ground at the edge byetching to form a mask 522. In the step of FIG. 5D, the surface of thegate insulating film 506 is etched by about 40 nm.

Then, the doping is effected with an impurity element for imparting then-type under the condition of an increased acceleration voltage bydecreasing the dosage to be smaller than that of the first dopingtreatment. For example, the acceleration voltage is set to be from 70 to120 keV, the dosage is set to be 1×10¹³/cm² thereby to form firstimpurity regions 524 to 527 having an increased impurity concentration,and second impurity regions 528 to 531 that are in contact with thefirst impurity regions 524 to 527. In this step, the impurity may turndown to the lower side of the conductive layers 518 to 521 of the secondshape, and the second impurity regions 528 to 531 may be overlapped onthe conductive layers 518 to 521 of the second shape. The impurityconcentration in the second impurity regions is from 1×10¹⁶ to 1×10¹⁸atoms/cm³ (FIG. 6A).

Referring to FIG. 6B, impurity regions 533 (533 a, 533 b) and 534 (534a, 534 b) of the conduction type opposite to the one conduction type areformed in the semiconductor layers 502, 505 that form the p-channelTFTs. In this case, too, an impurity element for imparting the p-type isadded using the conductive layers 518, 521 of the second shape as masksto form impurity regions in a self-aligned manner. At this moment, thesemiconductor layers 503 and 504 forming the n-channel TFTs are entirelycovered for their surfaces by forming a mask 532 of a resist. Here, theimpurity regions 533 and 534 are formed by the ion-doping method byusing diborane (B₂H₆). The impurity element for imparting the p-type isadded to the impurity regions 533 and 534 at a concentration of from2×10²⁰ to 2×10²¹ atoms/cm³.

If closely considered, however, the impurity regions 533, 534 can bedivided into two regions containing an impurity element that imparts then-type. Third impurity regions 533 a and 534 a contain the impurityelement that imparts the n-type at a concentration of from 1×10²⁰ to1×10²¹ atoms/cm³ and fourth impurity regions 533 b and 534 b contain theimpurity element that imparts the n-type at a concentration of from1×10¹⁷ to 1×10²⁰ atoms/cm³. In the impurity regions 533 b and 534 b,however, the impurity element for imparting the p-type is contained at aconcentration of not smaller than 1×10¹⁹ atoms/cm³ and in the thirdimpurity regions 533 a and 534 a, the impurity element for imparting thep-type is contained at a concentration which is 1.5 to 3 times as highas the concentration of the impurity element for imparting the n-type.Therefore, the third impurity regions work as source regions and drainregions of the p-channel TFTs without arousing any problem.

Referring next to FIG. 6C, a first interlayer insulating film 537 isformed on the conductive layers 518 to 521 of the second shape and onthe gate insulating film 506. The first interlayer insulating film 537may be formed of a silicon oxide film, a silicon oxynitride film, asilicon nitride film, or a laminated layer film of a combinationthereof. In any case, the first interlayer insulating film 537 is formedof an inorganic insulating material. The first interlayer insulatingfilm 537 has a thickness of 100 to 200 nm. When the silicon oxide filmis used as the first interlayer insulating film 537, TEOS and O₂ aremixed together by the plasma CVD method, and are reacted together undera pressure of 40 Pa at a substrate temperature of 300 to 400° C. whiledischarging the electric power at a high frequency (13.56 MHz) and at apower density of 0.5 to 0.8 W/cm². When the silicon oxynitride film isused as the first interlayer insulating film 537, this siliconoxynitride film may be formed from SiH₄, N₂O and NH₃, or from SiH₄ andN₂O by the plasma CVD method. The conditions of formation in this caseare a reaction pressure of from 20 to 200 Pa, a substrate temperature offrom 300 to 400° C. and a high-frequency (60 MHz) power density of from0.1 to 1.0 W/cm². As the first interlayer insulating film 537, further,there may be used a hydrogenated silicon oxynitride film formed by usingSiH₄, N₂O and H₂. The silicon nitride film, too, can similarly be formedby using SiH₄ and NH₃ by the plasma CVD method.

Then, a step is conducted for activating the impurity elements thatimpart the n-type and the p-type added at their respectiveconcentrations. This step is conducted by thermal annealing method usingan annealing furnace. There can be further employed a laser annealingmethod or a rapid thermal annealing method (RTA method). The thermalannealing method is conducted in a nitrogen atmosphere containing oxygenat a concentration of not higher than 1 ppm and, preferably, not higherthan 0.1 ppm at from 400 to 700° C. and, typically, at from 500 to 600°C. In this embodiment, the heat treatment is conducted at 550° C. for 4hours. When a plastic substrate having a low heat resistance temperatureis used as the substrate 501, it is desired to employ the laserannealing method.

Following the step of activation, the atmospheric gas is changed, andthe heat treatment is conducted in an atmosphere containing 3 to 100% ofhydrogen at from 300 to 450° C. for from 1 to 12 hours to hydrogenatethe semiconductor layer. This step is to terminate the dangling bonds of10¹⁶ to 10¹⁸/cm³ in the semiconductor layer with hydrogen that isthermally excited. As another means of hydrogenation, the plasmahydrogenation may be executed (using hydrogen excited with plasma). Inany way, it is desired that the defect density in the semiconductorlayers 502 to 505 is suppressed to be not larger than 1×10¹⁶/cm³. Forthis purpose, hydrogen may be added in an amount of from 0.01 to 0.1atomic %.

Then, a second interlayer insulating film 538 of an organic insulatingmaterial is formed maintaining an average thickness of from 1.0 to 2.0μm. As the organic resin material, there can be used polyimide, acrylicresin, polyamide, polyimideamide and BCB (benzocyclobutene). When thereis used, for example, a polyimide of the type that is heat polymerizedafter being applied onto the substrate, the second interlayer insulatingfilm is formed being fired in a clean oven at 300° C. When there is usedan acrylic resin, there is used the one of the two-can type. Namely, themain material and a curing agent are mixed together, applied onto thewhole surface of the substrate by using a spinner, pre-heated by using ahot plate at 80° C. for 60 seconds, and are fired at 250° C. for 60minutes in a clean oven to form the second interlayer insulating film.

Next, the passivation film 539 is formed. In this embodiment, thesilicon nitride film is used as a passivation film 539. In the casewhere the second interlayer insulating film 538 includes an organicresin material, it is particularly effective to provide the passivationfilm 539 since the organic resin material contains a large amount ofmoisture.

Here, the conductive metal film is formed by sputtering and vacuumvaporization and is patterned by using a mask and is, then, etched toform source wirings 540 to 543, drain wirings 544 to 546. Further,though not diagramed in this embodiment, the wiring is formed by alaminate of a 50 nm thick Ti film and a 500 nm thick alloy film (alloyfilm of Al and Ti).

Then, a transparent conductive film is formed thereon maintaining athickness of 80 to 120 nm, and is patterned to form a pixel electrode547 (FIG. 7A). Therefore, the pixel electrode 547 is formed by using anindium tin-oxide (ITO) film as a transparent electrode or a transparentconductive film obtained by mixing 2 to 20% of a zinc oxide (ZnO) intoindium oxide. The pixel electrode 547 functions as an anode of a lightemitting element. Further, the pixel electrode 547 is formed being incontact with, and overlapped on, the drain wiring 546 that iselectrically connected to the drain region of the driving TFT.

Next, as shown in FIG. 7B, the third interlayer insulating film 548having an opening portion at the position corresponding to the pixelelectrode 547 is formed. In this embodiment, side walls having a taperedshape are formed by using a wet etching method in forming the openingportion. Differently from the case shown in this embodiment, the organiclight emitting layer formed on the third interlayer insulating film 548is not separated. Thus, the deterioration of the organic light emittinglayer which derives from a step becomes a conspicuous problem if theside walls of the opening portion are not sufficiently gentle, whichrequires attention.

Although a film from silicon oxide film is used in this embodiment forthe third interlayer insulating film 548, organic resin films such aspolyimide, polyamide, acrylic, BCB (benzocycrobutene), or silicon oxidefilm may also be used in some cases.

Then, it is preferable that, before the organic light emitting layer 550is formed on the third interlayer insulating film 548, plasma processingusing argon is conducted to the surface of the third interlayerinsulating film 548 to make close the surface of the third interlayerinsulating film 548. With the above structure, it is possible to preventmoisture from permeating the organic light emitting layer 550 from thethird interlayer insulating film 548.

An organic light emitting layer 550 is formed by evaporation. A cathode(MgAg electrode) 551 and a protective electrode 552 are also formed byevaporation. Desirably, heat treatment is performed on the pixelelectrode 547 to remove moisture completely from the electrode beforeforming the organic light emitting layer 550 and the cathode 551. Thoughthe cathode of OLED is a MgAg electrode in this embodiment, other knownmaterials may be used instead.

A known material can be used for the organic light emitting layer 550.For example, a low molecular weight organic EL material or a highmolecular weight organic EL material can be used. The organic lightemitting layer may be a thin film formed of a light emitting materialthat emits light from singlet excitation (fluorescence) (the material iscalled a singlet compound) or a light emitting material that emits lightfrom triplet excitation (phosphorescence) (the material is called atriplet compound). In this embodiment, the organic light emitting layerhas a two-layer structure consisting of a hole transporting layer and alight emitting layer. The organic light emitting layer may additionallyhave one or more layers out of a hole injection layer, an electroninjection layer, and an electron transporting layer. Variouscombinations have been reported and the organic light emitting layer ofthis embodiment can take any of those.

The hole transporting layer of this embodiment is formed by evaporationfrom polyphenylene vinylene. The light emitting layer of this embodimentis formed by evaporation from polyvinyl carbazole with 30 to 40% of PBD,that is a 1,3,4-oxadiazole derivative, being molecule-dispersed. Thelight emitting layer is doped with about 1% of Coumarin 6 as greenluminescent center.

The protective electrode 552 alone can protect the organic lightemitting layer 550 from moisture and oxygen, but it is more desirable toadd a protective film 553. This embodiment uses a silicon nitride filmwith a thickness of 300 nm as the protective film 553. The protectivefilm and the protective electrode 552 may be formed in successionwithout exposing the device to the air.

The protective electrode 552 also prevents degradation of the cathode551. A typical material of the protective electrode is a metal filmmainly containing aluminum. Other materials may of course be used. Sincethe organic light emitting layer 550 and the cathode 551 are extremelyweak against moisture, the organic light emitting layer, the cathode,and the protective electrode 552 are desirably formed in successionwithout exposing them to the air. The organic light emitting layer andthe cathode are thus protected from the outside air.

The organic light emitting layer 550 is 10 to 400 nm in thickness(typically 60 to 150 nm), and the cathode 551 is 80 to 200 nm inthickness (typically 100 to 150 nm).

The passivation film 539 is effective in preventing moisture containedin the second interlayer insulating film 538 from seeping into theorganic light emitting layer 550 through the pixel electrode 547 and thethird interlayer insulating film 548 that are formed after thepassivation film is formed.

Thus completed is an active matrix substrate structured as shown in FIG.7B. An area 554 where the pixel electrode 547, the organic lightemitting layer 550, and the cathode 551 overlap corresponds to the OLED.

In this embodiment, the anode serves as the pixel electrode while thecathode is laid on the organic light emitting layer. Therefore lightfrom the OLED is emitted through the substrate to the outside.Alternatively, the cathode may serve as the pixel electrode while theanode is laid on the organic light emitting layer so that light isemitted in the direction reverse to the light emission direction of thisembodiment.

The active matrix substrate shown in FIG. 7B may be applied to thesubstrate 401 of Embodiment 1 to complete an OLED module. Needless tosay, the method of manufacturing the active matrix substrate of thepresent invention is not limited to the one described in thisembodiment. The active matrix substrate of the present invention may bemanufactured by a known method.

A p-channel TFT 560 and an n-channel TFT 561 are TFTs of the drivingcircuit and constitute a CMOS circuit. A switching TFT 562 and a drivingTFT 563 are TFTs of the pixel portion. The TFTs of the driving circuitand the TFTs of the pixel portion can be formed on the same substrate.

In the case of a light-emitting device using the OLED of thisembodiment, its driving circuit can be operated by a power supply havinga voltage of about 5 to 6 V, 10 V, at most. Therefore degradation ofTFTs due to hot electron is not a serious problem. Also, smaller gatecapacitance is preferred for the TFTs since the driving circuit needs tooperate at high speed. Accordingly, in a driving circuit of alight-emitting device using an OLED as in this embodiment, the secondimpurity region 529 and the fourth impurity region 533 b of thesemiconductor layers of the TFTs preferably do not overlap the gateelectrode 518 and the gate electrode 519, respectively.

Embodiment 3

The light-emitting device is of the self-emission type, and thusexhibits more excellent recognizability of the displayed image in alight place as compared to the liquid crystal display device.Furthermore, the light-emitting device has a wider viewing angle.Accordingly, the light-emitting device can be applied to a displayportion in various electronic devices.

Such electronic devices using a light-emitting device of the presentinvention include a video camera, a digital camera, a goggles-typedisplay (head mount display), a navigation system, a sound reproductiondevice (a car audio equipment and an audio set), note-size personalcomputer, a game machine, a portable information terminal (a mobilecomputer, a portable telephone, a portable game machine, an electronicbook, or the like), an image reproduction apparatus including arecording medium (more specifically, an apparatus which can reproduce arecording medium such as a digital video disc (DVD) and so forth, andincludes a display for displaying the reproduced image), or the like. Inparticular, in the case of the portable information terminal, use of thelight-emitting device is preferable, since the portable informationterminal that is likely to be viewed from a tilted direction is oftenrequired to have a wide viewing angle. FIG. 8 respectively shows variousspecific examples of such electronic devices.

FIG. 8A illustrates an organic light emitting display device whichincludes a casing 2001, a support table 2002, a display portion 2003, aspeaker portion 2004, a video input terminal 2005 or the like. Thepresent invention is applicable to the display portion 2003. Thelight-emitting device is of the self-emission type and thereforerequires no back light. Thus, the display portion thereof can have athickness thinner than that of the liquid crystal display device. Theorganic light emitting display device is including all of the displaydevice for displaying information, such as a personal computer, areceiver of TV broadcasting and an advertising display.

FIG. 8B illustrated a digital still camera which includes a main body2101, a display portion 2102, an image receiving portion 2103, anoperation key 2104, an external connection port 2105, a shutter 2106, orthe like. The light-emitting device in accordance with the presentinvention can be used as the display portion 2102.

FIG. 8C illustrates a laptop computer which includes a main body 2201, acasing 2202, a display portion 2203, a keyboard 2204, an externalconnection port 2205, a pointing mouse 2206, or the like. Thelight-emitting device in accordance with the present invention can beused as the display portion 2203.

FIG. 8D illustrated a mobile computer which includes a main body 2301, adisplay portion 2302, a switch 2303, an operation key 2304, an infraredport 2305, or the like. The light-emitting device in accordance with thepresent invention can be used as the display portion 2302.

FIG. 8E illustrates an image reproduction apparatus including arecording medium (more specifically, a DVD reproduction apparatus),which includes a main body 2401, a casing 2402, a display portion A2403, another display portion B 2404, a recording medium (DVD or thelike) reading portion 2405, an operation key 2406, a speaker portion2407 or the like. The display portion A 2403 is used mainly fordisplaying image information, while the display portion B 2404 is usedmainly for displaying character information. The light-emitting devicein accordance with the present invention can be used as these displayportions A and B. The image reproduction apparatus including a recordingmedium further includes a game machine or the like.

FIG. 8F illustrates a goggle type display (head mounted display) whichincludes a main body 2501, a display portion 2502, an arm portion 2503.The light-emitting device in accordance with the present invention canbe used as the display portion 2502.

FIG. 8G illustrates a video camera which includes a main body 2601, adisplay portion 2602, a casing 2603, an external connecting port 2604, aremote control receiving portion 2605, an image receiving portion 2606,a battery 2607, a sound input portion 2608, an operation key 2609, orthe like. The light-emitting device in accordance with the presentinvention can be used as the display portion 2602.

FIG. 8H illustrates a mobile phone which includes a main body 2701, acasing 2702, a display portion 2703, a sound input portion 2704, a soundoutput portion 2705, an operation key 2706, an external connecting port2707, an antenna 2708, or the like. The light-emitting device inaccordance with the present invention can be used as the display portion2703. Note that the display portion 2703 can reduce power consumption ofthe portable telephone by displaying white-colored characters on ablack-colored background.

When the brighter luminance of light emitted from the organic lightemitting material becomes available in the future, the light-emittingdevice in accordance with the present invention will be applicable to afront-type or rear-type projector in which light including output imageinformation is enlarged by means of lenses or the like to be projected.

The aforementioned electronic devices are more likely to be used fordisplay information distributed through a telecommunication path such asInternet, a CATV (cable television system), and in particular likely todisplay moving picture information. The light-emitting device issuitable for displaying moving pictures since the organic light emittingmaterial can exhibit high response speed.

A portion of the light-emitting device that is emitting light consumespower, so it is desirable to display information in such a manner thatthe light emitting portion therein becomes as small as possible.Accordingly, when the light-emitting device is applied to a displayportion which mainly displays character information, e.g., a displayportion of a portable information terminal, and more particular, aportable telephone or a sound reproduction device, it is desirable todrive the light-emitting device so that the character information isformed by a light emitting portion while a non-emission portioncorresponds to the background.

As set forth above, the present invention can be applied variously to awide range of electronic devices in all fields. The electronic device inthis embodiment can be obtained by utilizing a light-emitting devicehaving the configuration in Embodiments 1 or 2.

Embodiment 4

The example shown in Embodiment Mode 1 is of forming the DLC film byplasma CVD. This embodiment shows an example of forming on the wrappingfilm by sputtering a silicon nitride film containing Ar, anAr-containing film of a compound expressed as AlN_(X)O_(Y), an AlN filmcontaining Ar, or a laminate of these films. The description is givenwith reference to FIG. 9. Here, an Ar-containing film of a compoundexpressed as AlN_(X)O_(Y) is used to provide the inside of a wrappingfilm shaped like a sack or an empty box.

A chamber 901 connected to the earth is exhausted to reach vacuum andoxygen gas and inert gas (Ar gas or nitrogen gas) is introduced into thechamber. Then a film 906 of a compound expressed as AlN_(X)O_(Y) (thefilms is called an AlN_(X)O_(Y) film) with a rare gas element containedtherein is formed and used to provide the inside of a wrapping film 905.The wrapping film 905 is fixed by a holder 907 between a targetelectrode 903 and the chamber 901. The target electrode 903 is connectedto an RF power supply 904 and formed of AlN. Note that the outside ofthe wrapping film 905 is not provided with the AlN_(X)O_(Y) film.

The wrapping film 905 that is provided with the AlN_(X)O_(Y) film 906containing rare gas is thermally press-fit in vacuum to seal thelight-emitting device. By containing the rare gas, the film can beflexible and therefore can be prevented from developing a crack whenused to provide the wrapping film and thermally press-fit in vacuum.

If an AlN film is formed instead, inert gas (Ar gas or nitrogen gas) isintroduced into the chamber and a target electrode formed of AlN andconnected to the RF power supply is used. If a silicon nitride film isformed instead, nitrogen gas and Ar gas are introduced into the chamberand a target electrode formed of Si and connected to the RF power supplyis used.

Although the wrapping film 905 shown here is like a sack or an emptybox, the wrapping film may be composed of two sheets laid on top of eachother and the four sides thereof are all press-fit. The material usableas the wrapping film 905 is a resin material (polyester, polycarbonate,polypropylene, polyvinyl chloride, polystyrene, polyacrylonitrile,polyethylene terephthalate, nylon, etc.). Typically, thermoplastic, aPVF (polyvinyl fluoride) film, a Mylar film, or an acrylic resin film isused.

The target electrode shown in FIG. 9 is rod-like (cylinder-like orprism-like) but, needless to say, the shape of the target electrode isnot particularly limited. The target electrode is shaped in accordancewith the shape of the object to be processed since the distance betweenthe target electrode and the inner surface of the object to be processedis preferably kept constant.

The transmissivity of a AlN_(X)O_(Y) film (X<Y) having a thickness of100 nm is shown in FIG. 10. FIG. 10 shows that the AlN_(X)O_(Y) film hasa transmissivity of 80 to 90% in visible light range and is highlytransmissive of light. The AlN_(X)O_(Y) (X<Y) film contains 0.1 atomic %of rare gas element or higher, preferably 1 to 30 atomic %, and containsseveral atomic % of nitrogen or higher, preferably, 2.5 to 47.5 atomic%. The film preferably contains 2.5 to 47.5 atomic % of oxygen. Thenitrogen concentration and oxygen concentration of the film can becontrolled by suitably adjusting sputtering conditions (the substratetemperature, the type of gas introduced and the flow rate thereof, filmformation pressure, etc.).

If the sputtering conditions, for example, the flow rate of the gasintroduced, are changed, an AlN_(X)O_(Y) (X≧Y) film can be obtained. AAlN_(X)O_(Y) (X<Y) film or AlN_(X)O_(Y) (X≧Y) film that has a nitrogenor oxygen concentration gradient in the direction of the film thicknessmay also be formed.

FIG. 11 shows the transmissivity of an AlN film (also expressed asAl_(X)N_(Y) film) having a thickness of 100 nm. Although this film hasan average transmissivity lower than that of the AlN_(X)O_(Y) film (X<Y)shown in FIG. 10, the transmissivity thereof in visible light range is80 to 91.3% and is high enough. The acceptable range for theconcentration of impurities, oxygen, in particular, contained in theAl_(X)N_(Y) film is less than 0 to 10 atomic %. The oxygen concentrationcan be controlled by adjusting sputtering conditions (the substratetemperature, the type of gas introduced, the flow rate thereof, the filmformation pressure, etc.) appropriately. The Al_(X)N_(Y) film contains0.1 atomic % of rare gas element or higher, preferably 1 to 30 atomic %,and contains several atomic % of nitrogen or higher, preferably, 2.5 to47.5 atomic %. The film also contains 47.5 atomic % of oxygen or lower,preferably, equal to or higher than 0 atomic % and less than 10 atomic%.

If the sputtering conditions, for example, the flow rate of the gasintroduced, are changed, an Al_(X)N_(Y) film that has a nitrogen oroxygen concentration gradient in the direction of the film thickness mayalso be formed.

The following experiment has been conducted.

A polycarbonate (PC) film is provided with an Ar-containing AlN filmwith a thickness of 200 nm on one side. Another polycarbonate (PC) filmis provided with an Ar-containing AlN_(X)O_(Y) film with a thickness of200 nm on one side. Each of the films is bonded to a sealing can whileputting calcium oxide as a desiccant in the space between the film andthe sealing can. The thus prepared samples are let stand at roomtemperature for a long time and a change in weight is examined. If thereis a change in weight, it can be deduced that moisture or the like isadsorbed by the calcium oxide through the PC films. As a controlsubject, a sample is prepared by bonding a polycarbonate (PC) film aloneto a sealing can and placing calcium oxide between the film and the can.The results (transmissivity) of the experiment are shown in FIG. 12.

As shown in FIG. 12, the weight of the sample with the AlN film and theweight of the sample with the AlN_(X)O_(Y) film change less than thecontrol subject, i.e., the polycarbonate (PC) film alone. Accordingly,it can be concluded that the moisture resistance of a PC film isimproved by lining the PC film with an AlN film or an AlN_(X)O_(Y) film.

This embodiment may be combined with any of Embodiment Mode 2 andEmbodiments 1 through 3.

The present invention seals the entire substrate in vacuum on which anOLED is formed using a film that is provided with a flexible DLC film,silicon nitride film, AlN_(X)O_(Y) film, or AlN film on one side (insideor outside). The effect of preventing degradation of the OLED due tosteam or oxygen can thus be increased and the stability of the OLED canbe enhanced. Accordingly, a highly reliable light-emitting device can beobtained.

1. An electronic device comprising: a plurality of thin film transistorsformed over a substrate; a first film formed over the substrate and theplurality of thin film transistors, and covers at least two surfaces ofthe substrate, wherein a second film comprising a rare gas element andan inorganic material is formed between the first film and the pluralityof thin film transistors.
 2. An electronic device according to claim 1,wherein the first film is sealed at both edge portions thereof.
 3. Anelectronic device according to claim 1, wherein at least two portion ofthe first film are joined to each other.
 4. An electronic deviceaccording to claim 2, wherein at least one portion of the first film isfolded.
 5. An electronic device according to claim 3, wherein at leastone portion of the first film is folded.
 6. An electronic deviceaccording to claim 1, wherein the substrate comprises a plasticsubstrate.
 7. An electronic device according to claim 1, wherein thefirst film comprises a film selected from the group consisting of apolyethylene terephthalate (PET) film, a polyether sulfon (PES) film, apolyethylene naphthalate (PEN) film, a polycarbonate (PC) film, a nylonfilm, a polyether ether ketone (PEEK) film, a polysulfon (PSE) film, apolyether imide (PEI) film, a polyarylate (PAR) film, a polybuthyleneterephthalate (PBT) film, a thermoplastic film, a PVF (polyvinylfluoride) film, a polyester film, and an acrylic resin film.
 8. Anelectronic device according to claim 1, wherein the rare gas element isat least one selected from the group consisting of He, Ne, Ar, Kr andXe.
 9. An electronic device according to claim 1, wherein the electronicdevice is an organic light-emitting device.
 10. An electronic deviceaccording to claim 1, wherein the electronic device is at least oneselected from the group consisting of a digital camera, a personalcomputer, a mobile computer, an image reproduction apparatus, a goggletype display, a video camera and a mobile phone.
 11. An electronicdevice comprising: a plurality of thin film transistors formed over asubstrate; a first film formed over the substrate and the plurality ofthin film transistors, and covers at least one side surface of thesubstrate, wherein a second film comprising a rare gas element and acarbon is formed between the first film and the plurality of thin filmtransistors.
 12. An electronic device according to claim 11, wherein thefirst film is sealed at both edge portions thereof.
 13. An electronicdevice according to claim 11, wherein at least two portion of the firstfilm are joined to each other.
 14. An electronic device according toclaim 12, wherein at least one portion of the first film is folded. 15.An electronic device according to claim 13, wherein at least one portionof the first film is folded.
 16. An electronic device according to claim11, wherein the substrate comprises a plastic substrate.
 17. Anelectronic device according to claim 11, wherein the first filmcomprises a film selected from the group consisting of a polyethyleneterephthalate (PET) film, a polyether sulfon (PES) film, a polyethylenenaphthalate (PEN) film, a polycarbonate (PC) film, a nylon film, apolyether ether ketone (PEEK) film, a polysulfon (PSF) film, a polyetherimide (PEI) film, a polyarylate (PAR) film, a polybuthyleneterephthalate (PBT) film, a thermoplastic film, a PVF (polyvinylfluoride) film, a polyester film, and an acrylic resin film.
 18. Anelectronic device according to claim 11, wherein the rare gas element isat least one selected from the group consisting of He, Ne, Ar, Kr andXe.
 19. An electronic device according to claim 11, wherein theelectronic device is an organic light-emitting device.
 20. An electronicdevice according to claim 11, wherein the electronic device is at leastone selected from the group consisting of a digital camera, a personalcomputer, a mobile computer, an image reproduction apparatus, a goggletype display, a video camera and a mobile phone.
 21. An electronicdevice comprising: a plurality of thin film transistors formed over asubstrate; a first film wrapping the substrate and the plurality of thinfilm transistors, wherein an inner surface facing the substrate of thefirst film is covered with a second film comprising a rare gas elementand a silicon oxynitride.
 22. An electronic device according to claim21, wherein the first film is sealed at both edge portions thereof. 23.An electronic device according to claim 21, wherein at least two portionof the first film are joined to each other.
 24. An electronic deviceaccording to claim 22, wherein at least one portion of the first film isfolded.
 25. An electronic device according to claim 24, wherein at leastone portion of the first film is folded.
 26. An electronic deviceaccording to claim 21, wherein the substrate comprises a plasticsubstrate.
 27. An electronic device according to claim 21, wherein thefirst film comprises a film selected from the group consisting of apolyethylene terephthalate (PET) film, a polyether sulfon (PES) film, apolyethylene naphthalate (PEN) film, a polycarbonate (PC) film, a nylonfilm, a polyether ether ketone (PEEK) film, a polysulfon (PSF) film, apolyether imide (PEI) film, a polyarylate (PAR) film, a polybuthyleneterephthalate (PBT) film, a thermoplastic film, a PVF (polyvinylfluoride) film, a polyester film, and an acrylic resin film.
 28. Anelectronic device according to claim 21, wherein the rare gas element isat least one selected from the group consisting of He, Ne, Ar, Kr andXe.
 29. An electronic device according to claim 21, wherein theelectronic device is an organic light-emitting device.
 30. An electronicdevice according to claim 21, wherein the electronic device is at leastone selected from the group consisting of a digital camera, a personalcomputer, a mobile computer, an image reproduction apparatus, a goggletype display, a video camera and a mobile phone.
 31. An electronicdevice comprising: a plurality of thin film transistors formed over asubstrate; a first film wrapping the substrate and the plurality of thinfilm transistors, wherein an inner surface facing the substrate of thefirst film is covered with a second film comprising a rare gas elementand a silicon nitride.
 32. An electronic device according to claim 31,wherein the first film is sealed at both edge portions thereof.
 33. Anelectronic device according to claim 31, wherein at least two portion ofthe first film are joined to each other.
 34. An electronic deviceaccording to claim 32, wherein at least one portion of the first film isfolded.
 35. An electronic device according to claim 33, wherein at leastone portion of the first film is folded.
 36. An electronic deviceaccording to claim 31, wherein the substrate comprises a plasticsubstrate.
 37. An electronic device according to claim 31, wherein thefirst film comprises a film selected from the group consisting of apolyethylene terephthalate (PET) film, a polyether sulfon (PES) film, apolyethylene naphthalate (PEN) film, a polycarbonate (PC) film, a nylonfilm, a polyether ether ketone (PEEK) film, a polysulfon (PSF) film, apolyether imide (PEI) film, a polyarylate (PAR) film, a polybuthyleneterephthalate (PBT) film, a thermoplastic film, a PVF (polyvinylfluoride) film, a polyester film, and an acrylic resin film.
 38. Anelectronic device according to claim 31, wherein the rare gas element isat least one selected from the group consisting of He, Ne, Ar, Kr andXe.
 39. An electronic device according to claim 31, wherein theelectronic device is an organic light-emitting device.
 40. An electronicdevice according to claim 31, wherein the electronic device is at leastone selected from the group consisting of a digital camera, a personalcomputer, a mobile computer, an image reproduction apparatus, a goggletype display, a video camera and a mobile phone.
 41. An electronicdevice comprising: a plurality of thin film transistors formed over asubstrate; a first film wrapping the substrate and the plurality of thinfilm transistors, wherein an inner surface facing the substrate of thefirst film is covered with a second film comprising a rare gas elementand an AlN_(X)O_(Y).
 42. An electronic device according to claim 41,wherein the first film is sealed at both edge portions thereof.
 43. Anelectronic device according to claim 41, wherein at least two portion ofthe first film are joined to each other.
 44. An electronic deviceaccording to claim 42, wherein at least one portion of the first film isfolded.
 45. An electronic device according to claim 43, wherein at leastone portion of the first film is folded.
 46. An electronic deviceaccording to claim 41, wherein the substrate comprises a plasticsubstrate.
 47. An electronic device according to claim 41, wherein thefirst film comprises a film selected from the group consisting of apolyethylene terephthalate (PET) film, a polyether sulfon (PES) film, apolyethylene naphthalate (PEN) film, a polycarbonate (PC) film, a nylonfilm, a polyether ether ketone (PEEK) film, a polysulfon (PSF) film, apolyether imide (PEI) film, a polyarylate (PAR) film, a polybuthyleneterephthalate (PBT) film, a thermoplastic film, a PVF (polyvinylfluoride) film, a polyester film, and an acrylic resin film.
 48. Anelectronic device according to claim 41, wherein the rare gas element isat least one selected from the group consisting of He, Ne, Ar, Kr andXe.
 49. An electronic device according to claim 41, wherein theelectronic device is an organic light-emitting device.
 50. An electronicdevice according to claim 41, wherein the electronic device is at leastone selected from the group consisting of a digital camera, a personalcomputer, a mobile computer, an image reproduction apparatus, a goggletype display, a video camera and a mobile phone.
 51. An electronicdevice comprising: a plurality of thin film transistors formed over asubstrate; a first film wrapping the substrate and the plurality of thinfilm transistors, wherein an inner surface facing the substrate of thefirst film is covered with a second film comprising a rare gas elementand an AlN.
 52. An electronic device according to claim 51, wherein thefirst film is sealed at both edge portions thereof.
 53. An electronicdevice according to claim 51, wherein at least two portion of the firstfilm are joined to each other.
 54. An electronic device according toclaim 52, wherein at least one portion of the first film is folded. 55.An electronic device according to claim 53, wherein at least one portionof the first film is folded.
 56. An electronic device according to claim51, wherein the substrate comprises a plastic substrate.
 57. Anelectronic device according to claim 51, wherein the first filmcomprises a film selected from the group consisting of a polyethyleneterephthalate (PET) film, a polyether sulfon (PES) film, a polyethylenenaphthalate (PEN) film, a polycarbonate (PC) film, a nylon film, apolyether ether ketone (PEEK) film, a polysulfon (PSF) film, a polyetherimide (PEI) film, a polyarylate (PAR) film, a polybuthyleneterephthalate (PBT) film, a thermoplastic film, a PVF (polyvinylfluoride) film, a polyester film, and an acrylic resin film.
 58. Anelectronic device according to claim 51, wherein the rare gas element isat least one selected from the group consisting of He, Ne, Ar, Kr andXe.
 59. An electronic device according to claim 51, wherein theelectronic device is an organic light-emitting device.
 60. An electronicdevice according to claim 51, wherein the electronic device is at leastone selected from the group consisting of a digital camera, a personalcomputer, a mobile computer, an image reproduction apparatus, a goggletype display, a video camera and a mobile phone.
 61. An electronicdevice, comprising: a transistor formed over a substrate, an insulatinglayer formed over the transistor, a first film covering the insulatinglayer, a second film formed over the first film, and a flexible printedsubstrate attached to the substrate, wherein the second film comprises arare gas element and an inorganic material, wherein the first filmcovers bottom and side surfaces of the substrate, wherein the first filmcomprises an opening, wherein the flexible printed substrate extendsbeyond a side edge of the substrate, a side edge of the first film, anda side edge of the second film, and wherein the flexible printedsubstrate is electrically connected to the transistor through theopening.
 62. An electronic device, comprising: a substrate a lightemitting device formed over the substrate, a lead-out wiring line, afirst film, a second film, and a flexible printed substrate attached tothe substrate, wherein the second film comprises a rare gas element andan inorganic material, wherein the second film is formed over the firstfilm, wherein the first film wraps the light emitting device, whereinthe first film comprises an opening, wherein the flexible printedsubstrate extends beyond a side edge of the substrate, a side edge ofthe first film, and a side edge of the second film, and wherein theflexible printed substrate is electrically connected to the lead-outwiring line through the opening.
 63. An electronic device, comprising:at least one transistor formed over a substrate; a protective filmformed over the at least one transistor; a first film formed so as tocover the protective film; a wrapping film formed around the first film;a second film formed around the wrapping film; and a flexible printedsubstrate, wherein the second film comprises a rare gas element and aninorganic material, wherein the first film is formed in contact with andcovers a bottom surface and side surfaces of the substrate, wherein thefirst film includes an opening therein, and wherein the flexible printedsubstrate is formed through the opening in the first film and iselectrically connected to the transistor through the opening.
 64. Thedevice of claim 63, further comprising a base film formed between thesubstrate and the at least one transistor.
 65. The device of claim 63,further comprising an interlayer insulating layer formed on the at leastone transistor.
 66. The device of claim 65 further comprising a pixelelectrode formed on the interlayer insulating layer.
 67. The device ofclaim 66 further comprising an insulating film formed on the pixelelectrode, the insulating film having an opening therein above the pixelelectrode and an organic light emitting layer formed in the opening, anda cathode formed on the organic light emitting layer, wherein theprotective film is formed on the insulating film and the cathode. 68.The device of claim 67, wherein the pixel electrode, the organic lightemitting layer and the cathode form an OLED.